Process of sealing-off vessels containing gas



Sept. 17, 1935. M. DE NEUMANN PROCESS OF SEALING-OFF VESSELS CONTAINING GAS Filed Aug. 9, 1953 INVENTOR M I HALY DE NEUMANN ATTORNEYS Patented Sept. 17, 1 935 PATENT oFFicE PROCESS OF SEALING-OFF VESSELS CONTAINING GAS Mihaly dc Neumann, Budapest, Hungary, as-

signor to Egyesiilt lzzolampa s Villamossagi Rszvnytarsasay Ujpest, Hungary Application August 9,

1933, Serial No. 684,365

In Germany June 17, 1932 6 Claims.

"glass or the like, which can be softened or fused by heating, although the bulb itself may and usu' ally does also consist of a vitreous substance, such as for example glass. The term gas in the following specification and claims is meant to in- I elude any substance which can be present in the gaseous phase at room temperature.

The process according to my invention is intended to be used and is of special importance in cases in which the pressure of the gas in the bulb no of the lamp, during the process of sealing-off is greater than the pressure of the external atmosphere, that is to say, when the lamp bulb which is being sealed off, is under an internal pressure exceeding 760 mm. mercury. The present process can be carried out in a simple manner, with but little departure from the process used heretofore for similar purposes.

The process of my invention is intended for sealing-on gas-filled electric incandescent lamps and the like, as will be fully explained herein after, by way of example, in connection with the sealing-01f of such lamps, with reference to the accompanying drawing, in which Fig. 1 shows the method heretofore used for the sealing of such lamps, g

' Fig. 2 is a plan view of an arrangement suitable for carrying out the present process;

Fig. 3 shows the same arrangement in side elevation and partly in section;

Figs. 4 and 5 show different stages in the progress of the process, Fig. 4 being an elevation and Fig. 5 a plan view;

Figs. 6 and 7 show, in front and in side elevation, respectively, the sealed-oil pump tube of the lamp;

Figs. 8 and 9 show the same tube after separa tion;

Figs. 10 and 11 show two constructional forms of pinching or tube closing tools used for pinching off the tube;

Figs. 12 and 13 are two views of the pump tube showing the same pinched together but not yet severed or separated;

Figs. 14 and 15'show the same tube after separation and finally,

Fig. 16 shows a pump tube which has been severed below the level of the sealing-off pinch previously produced.

In order to render the process according to my invention readily understood, it is first necessary 5 to briefly state how gas-filled incandescent lamps are usually sealed at present, and have been sealed heretofore, in connection with Fig. 1 of the drawing. This figure shows the glass bulb l of the lamp provided with the socket 2 and the fill- 1o ing tube 3, also made of glass, connected with the bulb in the usual manner by being fused to the inside of the socket 2 and thereafter blown out. The glass tube ii is connected on its lower part 3' by means of the connecting-piece 1, made of rub- 15.

her, with the tube it leading to the exhaustingpump or the supply of filling gas, not shown. When the bulb I has been filled withgas, the tube 3 is heated, in a manner wellknown to those skilled in the art, on its part 5 by gas-flames from 20 the burners E to a temperature above the softening temperature of its material. The bulb l being filled with gas at a pressure'below the atmospheric pressure, the external pressure of the air readily deforms the softened walls of the tube 3, so thatthey are pressed and fused together and thus airtightly seal the lamp, thereby effecting the first step of the known process, the airtight sealing. On further heating, the tube, under the influence of the surface tension of the softened 30 glass, is being parted in two, thereby completing the second step of the known process, the separation.

It is obvious that the process just described is applicable only to the sealing-off of lamps and the like wherein the pressure in the interior of the bulb is lower than the pressure outside it. In the usual automatic manufacturing processes lamps are filled with gas immediately after they have been exhausted. During the filling operation and subsequent sealing-off of the lamp the temperature of the bulb, notwithstanding cooling, is far above room temperature, while the internal pressure must, of necessity, be less than atmospheric pressure. Thus, in view of the fact that the pressure of the gas inside the lamp bulb becomes still less when the bulb cools down after sealing-off, only those lamps in which the pressure ofthe gas-filling does not exceed that of 600 m. m. of mercury can be made by the known process referred to above.

My invention is based upon the-discovery that lamp bulbs, which during the process of sealing off are under an internal gas pressure greater than that of atmosphere can, in fact, be sealed oil in a similar manner provided that the actual closure of the pump tube, that is, the step which constitutes the first phase of the sealing-off operation, is not left for the surface tension of the softened glass or for the pressure of the external air to accomplish, but is carried out by compressing the pump tube, previously softened to an appropriate degree of plasticity, by means of a suitable tool, or several such tools. If the heating of the glass tube be suitably carried out, a state is arrived at or a moment can be found in which the glass is not yet so soft that the superatmospheric pressure inside the tube will blow it out during the short period required for the closing operation but is alreadysuiliciently plastic to permit of its being compressed without being broken or cracked and the tube closed by means of the suitable tool or tools just mentioned.

Referring now to Figs. 2 to 7, inclusive, the numeral 3 designates the pump tube, the lower part in fits and is connected to, the bore of the connecting-piece 4. The members I and l together constitute the pinching tool, which consists of two parts and may be heated in any suitable way, for example by the flames of the same gas burners 8, or of other gas burners, not shown, or electrically. This tool, when its parts are moved, respectively, in the directions indicated by the arrows 8 and 8' of Figs. 2, 4 and 5 squeezes the sides of the previously heated and sufllciently softened pump tube together. It has been found best not to continue to heat the pump tube during the actual pinching operation; indeedit is preferable to apply a current of air to the region of the pinch 31), Fig. 6, for the purpose of cooling down this portion of the tube. The heating may be stopped, for example by turning of! the gas of the burners 5, or reducing its pressure to shorten the flames, and/or inserting suitable screens between the burners 8 and the tube 3. The pinching tool may be so constructed as not only to compress the pump tube,

until the vessel is sealed. off airtightly, but also to divide the said tube into two parts, as shown in Figs. 6 and 'I. To this end the tool members I and I are provided with blades or cutting edges 9 and 9, see Figs. 4 and 5, so that they act like pincers. Finally the sealed-off and separated. bulb is removed by lifting it off the pump, see Fig. 8. A pump tube sealed off in this way exhibits an edge It as shown in Fig. 8. If desired, this edge may be rounded off by again heating the glass at this point to softening temperature. In this way the free edge of thetube acquires the shape indicated at III" in Fig. 9.

Tools of other shapes may also be used. For instance, tools l1, I! or 19 and I! having the sections shown in Figs. 10 and 11 have been found to be quite satisfactory. The tools preferably consist of suitable steel, which does not adhere to the hot glass, such steels being known in the art.

The tool may also be so constructed that it compresses the tube in more than two directions.

The exact moment when the tube 3 is plastic enough to be squeezed together, but not soft enough to be blown out by the internal gas pressure has to be determined by experiment, and the tool has to be moved as soon as possible after this has taken place.

The foregoing. example of one mode of carrying out the process according to my invention is one in which the sealing-oil of the pump tube and its severance are carried out in a single oper- The actual separation may then, of course, be 5 effected, when the tube is cold, by snapping off the free end at the pinch 3b. Figs. 14 and 15 show the appearance of the end of a pump tube snapped. oif in this way. In this case also the end of the tube may subsequently be heated to round it off. 111

The severing step may, of course, be omitted altogether, o'r severance may be effected below the point where the tube is pinched, as shown in Fig. 16. In this case, again, the end of thetube may be rounded off or fused by re-heating it. 15

In the methods of procedure thus far herein described the pinching of the pump tube has been assumed to be carried to the stage of completely closing the tube in an airtight manner. It is, however, also within the scope of the in- 20 vention so to carry out the pinching operation. that the tube is not completely closed but that a narrow opening or passageway still remains. The tube may then be heated up at this point, or below it, and thereby completely closed up and 25 separated oil". 1

The invention includes gas filled electric incandescent lamps, having an internal gas pressure exceeding the pressure of a 600 mm. mercury column and the characteristic features of a pump 30 tube compressed by means of a tool, i. e. partly flattened by said tool It is also characteristic of lamp bulbs, sealed by the process according to my invention, that the part where the pump tube is sealed off is flat- 35 tened on two or more sides and that there is a sharp edge II which is not rounded oil by the surface tension of the glass, inside the said pump tube, as shown on Figs. 7, 8, 9 and 12 to 16 inclusive. In most cases this edge terminates in the two sharp and well-defined corners not points 12 and 12, as shown in Figs. 7, 12 and 15, these not being rounded off by the surface tension of the glass.

I further wish it to be understood that I do 45 not desire to be limited to the exact ways of proceeding shown and described, only to the sealing of lamp bulbs filled with gas above atmospheric pressure, for obvious modifications will oc- ,cur to a person skilled in the art.

Having now fully described my invention I claim:

1. In the manufacture of gas-filled electric lamps, wherein the bulb of each lamp contains a gas under pressure greater than that of the atmosphere and is provided with a tube of vitre-- ous material connected to said bulb, the process for sealing-off the bulb by air-tightly closing said tube, which, in a combined group of steps, consists in heating said tube until it is plastic enough. to be compressed and be proof against fracture and breakage, and thereafter, while said heated tube is yet-sufliciently resistant to withstand being blownout by theinterior gas pressure, compressing and thereby closing the plastic tube by 65 means of a tool.

2. In the manufacture of gas-filled electric lamps, wherein the bulb of each lamp contam a gas under pressure greater than that of the t atmosphere and is provided with a tube of vitreous material connected to said bulb, the process for sealing-off the bulb by air-tightly closing said tube, which, in a combined group of steps, consists in heating said tube umzil it is plastic enough to be compressed and be proof against fracture and breakage, and thereafter, while said heated tube is yet sufficiently resistant to withstand being blown out by the interior-gas pressure, compressing and thereby closing the plastic tube by means of a hot tool.

3. In the manufacture of gas-filled electric lamps, wherein the bulb of each lamp contains a gas under pressure greater than that of the atmosphere and is provided with a tube of vitre ous material connected to said bulb, the process for sealing-E the bulb by air-tightly closing said tube, which, in a combined group of steps consists in heating said tube until it is plastic enough 4 to be compressed and be proof against fracture and breakage, simultaneously heating a tool, and, while said heated tube is yet sufficiently resistant to withstand being blown out by the interior gas pressure, compressing and thereby closing the plastic tube by means of said heated tool, and thereafter separating said tube into two parts.

4. In the manufacture: of gas-filled electric lamps, wherein the bulb of each lamp contains a gas under pressure greater than that of the atmosphere and is provided with a tube of vitreous material'connected to said bulb, the process for sealing-o3 the bulb by air-tightly closing said tube, which, in a combined group of steps, consists in heating said tube until it is plastic enough to be compressed and be proof against fracture and breakage, and thereafter, while said heated tube is yet sufliciently resistant to withstand being blown out by the interior gas pressure, compressing the plastic tube and alsoseparating the I 3 same by means accomplishing this in a single operation.

5. In the manufacture of gas-filled electric lamps, wherein the bulb of each lamp contains a gas under pressure greater than that of the 5 atmosphere and is provided with a tube of vitreous material connected to said bulb,'the process for sealing-off the bulb by air-tightly closing said tube, which, in a combined group of steps, consists in heating said tube until it is plastic enough to be compressed and be proof against fracture and breakage, and thereafter, while said heated tube is yet sufficiently resistant to withstand being blown out by the interior gas pressure, compressing and thereby closing the plastic tube by means of a pinching tool for compressing and.

separating said tube in a single operation.

6. In the manufacture of gas-filled electric I lamps, wherein the bulb of each lamp contains a gas under pressure greater than that of the atmosphere and is provided with a tube of vitreous material connected to said bulb, the process for sealing-off the bulb by air-tightly closing said tube, which, in a combined group of steps, consists in heating said tube until it is plastic enough MmALY n! NEUMANN. 

